Construction Of Bioelectrocatalytical System Based On Lipidic Cubic Phase And Applications In Bioelectronic Devices

Liquid-crystalline lipid cubic phase is formed by self-assembling of polar lipids in aqueous media.The internal structure consists of one congruent lipid bilayer, forming a three-dimensional and well-ordered structure interwoven by aqueous channels.The lipidic cubic phase is of high viscosity, good biocompatibility,and good stability in the presence of excess water.These special characteristics make it suitable for hosting the biocatalysts ( proteins or enzymes ) on electrode surface, and therefore establishing bioelectrocatalysis systems to build bioelectronic devices ( biosensors,biofuel cells etc. ).In this thesis,liquid crystal cubic phase formed with monoolein has been used as immobilizing matrix to host protein ( hemoglobin ),enzyme ( alcohol dehydrogenase, laccase ) on glass carbon electrode surface to construct bioelectronic devices.The details are summarized as follows:1. Liquid crystal cubic phase formed with monoolein has been used as immobilizing matrix to host redox protein hemoglobin. The direct electron transfer between hemoglobin and electrode was investigated and the third generation biosensor of hydrogen peroxide was constructed.Based on this system,the enhanced average kinetic electron transfer rate constant ks of 3.03 s?1 and the small apparent Michaelis-Menten constantΚaMpp of 0.27 mM were obtained. The proposed hydrogen peroxide biosensor showed a linear range of 7 ~239μM with a detection limit of 3.1μM.2. A modified electrode, MO-TCBQ/SWNT/GC, was constructed utilizing the lipidic cubic phase to immobilize Tetrachlorobenzoquinone ( TCBQ ) on SWNT-based electrode. A NADH sensor was constructed based on the electrocatalytic activity of TCBQ and NADH. The proposed NADH sensor showed a linear range of 5~1650μM with a detection limit of 0.82μM.A biosensor for the detection of ethanol was further constructed based on a bioelectrode MO-TCBQ-ADH/SWNT/GC utilizing the lipidic cubic phase to co-immobilize TCBQ and ADH on SWNT-modified electrode.The biosensor exhibits a wide linear dynamic range ( from 0.2 to 13 mM ),and low detection limit of 0.05 mM.3. A bioelectrode, MO-TB-ADH/GC,was prepared based on lipid cubic phase to co-entrap alcohol dehydrogenase and toluidine blue ( TB ).A bioanode was constructed based on the good electrocatalytic oxidation activity of the prepared bioelectrode toward ethanol.A biocathode,MO-Laccase/GC,was prepared with a similar methode.The electrode with Laccase as biocatalyst to reduce oxygen reduction.A new type of membrane-less ethanol/O2 biofuel cell has been constructed.At room temperature and under oxygen-saturation condition,the biofuel cell was found to have a open potential of 0.38 V and a power output of 0.2μW/cm2 under the work potential of 0.06 V.